The present invention relates to tape transport systems such as are used in magnetic tape reel-to-reel drives. The invention also relates to logical networks for producing quadrature pulse trains, and to motor control systems utilizing such pulse trains, both of the foregoing being particularly useful in the novel tape transport system described herein.
Reel-to-reel tape transport systems commonly employ pinch rollers or capstans which engage and directly drive the tape. The linear velocity of the tape is thus directly determined by the angular velocity of the pinch roller or capstan, so that if a constant tape linear velocity is desired for example, this is easily accomplished by maintaining a constant angular velocity of the pinch roller or capstan. While the control of the drive is thus relatively simple, such systems are subject to a number of drawbacks. For example, the direct contact of the pinch rollers and capstans with the tape tends to deform the tape and to increase its wear and tear. Further, pinch rollers and capstans are susceptible to malfunction or failure. They also involve significant manufacturing and maintenance costs.